1. Field of the Invention
The present invention relates to a resist composition, a resist film therefrom and a method of forming a negative pattern using the composition. More particularly, the present invention relates to a resist composition that finds application in, for example, a semiconductor production process for an IC or the like, a circuit board production process for a liquid crystal, a thermal head or the like and other photofabrication lithography processes, and also to a resist film from the composition and a method of forming a negative pattern using the composition.
2. Description of the Related Art
Since the development of the resist for a KrF excimer laser (248 nm), it has been of common practice to employ a pattern forming method through chemical amplification in order to compensate for any sensitivity deterioration caused by light absorption.
Heretofore, a vast variety of formulations have been proposed for the pattern forming method using a positive developer (namely, an alkali developer) and the positive resist composition for use in the method (see, for example, patent references 1 to 3). In addition, in recent years, research and development are being promoted for the pattern forming method using a negative developer (namely, a developer containing an organic solvent) and the negative resist composition for use in the method (see, for example, patent references 4 to 7).
Relatively favorable resist performance can be attained by employing the achieved formulations and developments. However, with respect to the depth of focus margin (DOF) in forming an isolated-contact-hole pattern, there is room for further improvements.
Herein, the expression “isolated-contact-hole pattern” refers to a pattern in which the inter-hole pitch is greater than twice the hole size.